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Putting Out the (Grass)
FireARS Scientists Use Other Methods to
Curb Weeds, Diseases on Grass Fields

Research leader Gary Banowetz
(left) and farmer Don Wirth
examine decomposing straw
after grass seed harvest.
ARS scientists have shown
that straw residue doesn't
have to be removed by burning
but can instead remain on the
field without reducing future
seed yields. (K11036-1)

Your front lawn has patches of bare dirt. You go to the
local nursery and get grass seed to fill these patches. But where do
the seeds actually come from?

The Pacific Northwest is home to most of the U.S. grass
seed farms, which produce more than 800 million pounds of seed annually.
This seed is sold in global markets, where it is used to produce turf,
forage for livestock, and grass buffers that provide conservation benefits.
Because U.S. and overseas markets demand high-quality pure seed, farmers
once routinely burned their fields after each season to control weeds
and diseasesalong with removing leftover straw from harvest.

The reduced air quality caused by burning eventually led
to legislation in some states that mandated limits on burning, beginning
in the mid-1980s. Grass seed straw is no longer burned in Washington,
while only about 10 percent of the grass-seed acres in Oregon are still
burned.

In the future, grass straw
may be a profitable energy
source. Technician Machelle
Nelson (left) and Oregon State
University cooperator Cynthia
Lipp sample a native grass for
analysis of compounds that
affect biomass quality when
the straw is converted to
energy products. (K11042-1)

Scientists at the ARS
National Forage Seed Production Research Center in Corvallis, Oregon,
have recently completed a 10-year study aimed at finding acceptable
alternatives for economically producing grass seed crops without use
of fire in western Oregon, where burning was first curtailed.

"This was a very successful project, and the results
are now being implemented," agronomist Jeffrey J. Steiner explains.

The researchers found not just one alternative to fire,
but rather a package of practices growers can choose from. For example,
they found that many seed growers could chop all their straw back onto
their fields and not reduce yields. They can also use no-till planting
without hurting seed yields. These practices have additional benefits
because they reduce soil erosion and enhance the habitat quality of
adjacent streams that harbor salmon protected under the Endangered Species
Act. Research by plant physiologist Stephen M. Griffith has shown that
the amount of nitrate-nitrogen in shallow ground water leaving seed
fields is reduced as much as 50 percent when no-till planting is in
use.

Microbiologist Karen Dierksen
harvests perennial ryegrass
tissue to look for proteins
expressed after the plants
are cut and dried in the
field before seed harvest.
Some of these proteins may
be useful for increasing
efficiency when straw is
used as a fermentation feedstock. (K11044-1)

The scientists also found that using no-till farming for
grass seed is significantly cheaper than conventional tillage because
it usually takes less energy and manpower to do it. Conventional tillage
requires many passes of equipment across the field to prepare the soil
for planting. Fortunately, the soils and climate of the Northwest allow
farmers to adopt no-till practices.

Farmers using no-till are doing so as a way to help clean
their fields by keeping crop and weed seeds from being buried by tillage
and to increase soil organic matter. Grass seed farmers using no-till
can also start planting a month earlier in the spring because the soil
is more stable than when traditional tillage is used in the fall.

One of the original reasons to burn the straw was to combat
blind seed disease. "This was a problem that threatened the entire
grass seed industry before farmers started burning their fields in 1948,"
according to plant pathologist Stephen C. Alderman. Farmers were worried
that during the phaseout of burning, the disease would reappear.

Agronomist George Mueller-Warrant
(front) and hydrologist Gerald
Whittaker look at weed
distribution patterns that
have changed over time with
the introduction of different
grass seed production practices. (K11039-1)

His research showed that the disease would not appear
on a large scale, and only low levels of the disease have appeared in
the last 10 years. He explains that growers are now using cultivars
that flower late in the spring when warm, dry weather conditions inhibit
the growth of the fungus that causes blind seed disease. Rainy summers
may produce a little more of the disease, as may the planting of older
cultivars. But overall, blind seed disease is under control.

As for weeds, farmers have had to adjust their management
practices without burning to control these pests. Agronomist George
W. Mueller-Warrant conducted research showing that certain weeds were
more easily controlled when the straw was chopped back onto the fields,
while other weeds required different herbicides for their control.

In general, weeds are still being adequately controlled.
He is now developing maps using geographic information system tools
and records from grass seed testing and cultivar certification organizations
to study how different weed distributions move through time over a large
region. Mueller-Warrant wants to find out why weeds grow in certain
areas but not others and use this information to develop better management
strategies.

Every year more than 1 million tons of straw are left
after grass seed fields are harvested. Straw has little direct economic
value to the seed farmers because it costs so much to transport.

Many farmers who do not chop their straw back onto their
fields sell itone-half million tonsto brokers who export
it to Asian markets, where it is used in livestock feed.

Looking for alternative ways for farmers to make a profit,
the scientists are studying methods of turning straw into electricity
or other value-added products, such as alcohol, on the farm, so that
it doesn't have to be shipped elsewhere for conversion. "We're
cooperating with a coalition of partners in Spokane County, Washington,
including farmers, industry, Bonneville Power Administration, and a
local utility company, as well as environmental groups, who will set
up an on-farm test facility to look at different ways to turn straw
into energy products," research leader Gary M. Banowetz says.

Just as farmers in the Midwest are turning corn into ethanol,
grass seed growers in the Pacific Northwest may be able to do the same
thing with straw. Banowetz explains that the process to turn straw into
alcohol is more difficultand more expensivethan with corn.
To reduce the costs, his laboratory has hired a postdoctoral researcher
to find genes that are turned on after grass is cut and combine portions
of these genes with genes that control cellulose-degrading enzymes to
speed the process of straw breakdown for faster fermentation. The laboratory
is also cooperating with engineers to make an on-farm reactor to turn
straw into gas that can be used to power a generator or to produce alcohol.

Even if farmers leave half the straw on the field to reduce
erosion, and the process of ethanol production is 70 percent efficient,
33 million gallons of ethanol could be produced annually from the remaining
grass straw of the Northwest, according to Banowetz.By David Elstein, Agricultural
Research Service Information Staff.